Earlier U.S. Pat. Nos. 4,833,010; 5,169,697; 4,938,817; and 4,683,593, owned by the common assignee herewith show part of the recent evolution in protective garments. As noted in the U.S. Pat. Nos. 4,833,010 and 5,169,697, hazardous materials handling personnel and particularly emergency response personnel are increasingly called upon to place themselves at risk in toxic and life threatening environments. Perhaps the most severe of these is associated with industrial accidents or spills involving materials which are unknown to the response team. In these environments the use of a totally encapsulating vapor protective suit is a virtual necessity. The development of the U.S. Pat. No. 4,833,010 material for use in such suits was a major step forward in enhancing the survival expectations of hazardous materials' response teams. For example, the breakthrough time for the U.S. Pat. No. 4,833,010 material is over eight hours for the chemicals tested under the ASTM F1001 Chemical Test Battery; however, previous suits made of PVC, Viton.RTM. chlorobutyl, butyl, or neoprene showed selective permeation of some of these chemicals in as little as two minutes. This, the U.S. Pat. No. 4,833,010 material substantially aided in resolving the dilemma facing an emergency team responding to an unknown hazard, however, as may be seen, the U.S. Pat. No. 4,833,010 material, like most other barrier materials is essentially thermoplastic in nature. Accordingly, an emergency response person responding to an incident involving unknown volatile and/or toxic chemicals would be at risk if a build-up of volatile vapors externally of the suit ignited. Such a "chemical flash fire" can generate intense heat of up to 2000.degree. F. for a few seconds, depending on the combustion material. Exposure of a thermoplastic or elastomeric chemical barrier suit to such temperatures would have instantaneous deleterious consequences.
As a result, chemical barrier suits which have a low thermal tolerance yet provide high chemical barrier protection are worn in conjunction with a second or oversuit made of a material such as metallized fiberglass or Nomex.RTM.. These metallized suits offer high reflectivity to reduce radiant energy transferred to the inner suit and high flame resistance to reduce heat transfer by convection and conduction to the inner suit but no chemical protection. Thus, by wearing two suits, hazardous materials' response personnel can escape from a flash fire with their chemical protection intact.
It has been recognized that wearing two suits, looking through two visors, etc. is less than desirable. Also, transporting and storing two suits for each of the response personnel is cumbersome and occupies valuable space on response vehicles. As would be expected, donning two suits materially increases the response time of the wearer. These problems are self-evident. One prior patent which ostensibly addresses such problems is U.S. Pat. No. 4,793,480 which discloses and claims a fabric and garment which assertedly would be useful in protective garments. However, the teachings of the patent do not address how the garment is to be made for the fabric, and the use of an outer layer of a polyethylene film seems an invitation to disaster upon flame impingement. That is, the outer layer is believed to be flammable and thus would serve to cause precisely the catastrophe it seeks to avoid. Thus the U.S. Pat. No. 4,792,480 patent does not present a usable material in actual practice and a need exists for a composite material which can be fabricated into a vapor protective suit for hazardous materials' response personnel which needs on adjunctive suit.